Instrumentation is known for borehole surveying to obtain geophysical and other data for oil and mining operations. It is usually necessary to know the orientation of the instrument package in the well for directional surveying or directional drilling. In apparatus of known construction orientation information is provided by a gyro or magnetic compass within the instrument package and associated with a photographic recorder operative to store and provide a record of compass readings for use after the instrument package is raised from the well. Information with respect to inclination is generally provided by a pendulous instrument associated with a photographic recorder to provide a record which is usable after the instrument package is removed from the well.
Instrumentation is also known for telemetering orientation data to the surface of a well. Gyro compasses have been employed to provide azimuth information, and with an electrical signal indication thereof being transmitted to the well surface. Gyro compasses are however relatively expensive and require energizing power for driving the gyro rotor. Other transducer structures have been provided for providing an electrical signal indication of orientation for transmission to the well surface. For example, in U.S. Pat. No. 3,622,971, a magnetic transducer is described for use in directional drilling and wherein a magnetic reference member is maintained in a stationary position during drilling operations and released during cessation of drilling to seek a different orientation and provide a signal indication thereof. Such transducer structure is relatively complicated and requires selective clamping and unclamping for operation with an associated drill string.